Your Instagram feed of still photos of your friends and their food might soon have video of those things too.

According to various reports, Instagram will add video to its popular photo-sharing service. The announcement is expected at the Facebook event being held tomorrow. Facebook, which bought Instagram for $1 billion in April 2012, sent mysterious invites to an event late last week via snail mail. "A small team has been working on a big idea. Join us for coffee and learn about a new product," the press invitation read.

Technology websites All Things D and TechCrunch have both independently reported that the Instagram team is planning to add video capabilities to the app. "The new video product is something that the service said it was planning to do for two years now, and there have been numerous rumors about it in recent weeks," Mike Isaac of All Things D reports.

When reached by ABC News, Facebook said it doesn't comment on rumors or speculation.

TechCrunch first reported that Facebook would release a new news reader app at the Thursday event, but now maintains that the event will be dedicated to just the new Instagram feature.

Details on how the service will work are slim. Though, Matthew Keys, the former social media editor at Reuters, reports on his blog that the feature would allow users to upload between five to 10 seconds of video.

Still, Instagram has a much larger built-in user base. The photo-sharing service has over 100 million active users, who upload around 40 million photos per day.

Since being acquired by Facebook, Instagram has still maintained an ad-free service. Back in December, when the company made changes to its Terms of Service and to the wording about advertising, there was user uproar and Instagram co-founder Kevin Systrom assured users that the company was listening to the strong feedback.

"We want to create meaningful ways to help you discover new and interesting accounts and content while building a self-sustaining business at the same time," Systrom said. Yesterday Facebook announced that it had 1 million active advertisers on the social network.

The Facebook event begins at 10 a.m. PT / 1:00 p.m. ET on Thursday, June 20. ABC News will have the latest then.